Modern vehicle transmissions include a number of planetary gear assemblies. The gear assemblies typically include a sun gear, planet gears and a ring gear configured to rotate with respect to a carrier. A pinion shaft is included in the center of the gear assembly. Carriers can include a bore for the pinion shaft. The bore can extend through the carrier housing. The more common method used to retain a pinion shaft with respect to axial or rotational movement in a carrier housing is to stake or upset the shaft material itself. This can create design issues especially for transmissions with aluminum parts as aluminum tends to expand more than steel under high temperatures. Other retainers for the pinion shaft, e.g., roll pins have been used in the past to retain the pinion shaft, however, such retainers can obstruct the travel of the pinion shaft and shaft place-holding devices used in assembly before the shaft is positioned as designed.
Other types of fasteners have been used in the past, e.g., as shown in U.S. Pat. No. 6,592,489 titled “Transmission Equipped with Planetary Gear Mechanism and Planetary Gear Mechanism,” which discloses the use of snap rings at various locations with respect to a carrier housing. Still, there is a need for a more high-volume-production-friendly process to hold the pinion shaft in position. Such retention means should be compatible with both the pre- and post-assembly requirements of the planetary gear assembly.